Do Humans Convert Vitamin K1 to Vitamin K2?

Chicken is a natural source of vitamin K-2.

Vitamin K sounds like one substance, yet it’s an umbrella term that includes several forms, including vitamin K-1 and vitamin K-2. To add to the potential confusion, there are multiple types of vitamin K-2. The differences are important because slight variations in their chemical structure mean that vitamins K-1 and K-2 likely have different jobs to fill in your body. Out of all the forms of vitamin K-2, one is created from vitamin K-1.

Vitamin K-1 Vs. Vitamin K-2

The most abundant form of vitamin K in your diet is vitamin K-1, which consists of just one substance known as phylloquinone. Vitamin K-2 is a little more complex because it’s another generic label that includes up to 12 forms of the vitamin collectively known as menaquinones. Vitamin K-1 and all the variations of vitamin K-2 are naturally occurring vitamins. Vitamin K-1 is produced by plants, while most forms of vitamin K-2 are synthesized by bacteria in the large intestine of animals and people.

Synthesis of Vitamin K-2

The different forms of vitamin K-2 are identified by numbers and carry the labels MK-1 through MK-12. Most of them are produced by bacteria without using vitamin K-1. As far as researchers know to date, only one of them, menaquinone-4 or MK-4, is converted from vitamin K-1. Turning the vitamin K-1 you consume into MK-4 does not involve bacteria; rather, it occurs in cells throughout your body. It’s likely that vitamin K is first converted into another form, menadione, then it’s metabolized into MK-4, according to the November 2013 issue of the “Journal of Biological Chemistry."

Benefits of Vitamin K-2

All forms of vitamin K can activate proteins responsible for making blood clot, but vitamin K-1 may be more active in that role than vitamin K-2. Vitamin K-2 is more important for maintaining strong bones than vitamin K-1, reported “Alternative Medicine Review” in March 2005. Researchers found that postmenopausal women who took 180 micrograms of vitamin K-2 in the form of MK-7 had less bone loss compared to women who did not take supplements, according to the September 2013 issue of “Osteoporosis International.”

Sources and Recommendations

The best sources of vitamin K-1 are green leafy vegetables and vegetable oils. You’ll only get vitamin K-2 from animal-based foods. Chicken is the best source, with 12 micrograms of vitamin K-2 in the form of MK-4 in a 3-ounce serving of chicken breast. The same portion of ham has 8 micrograms, while beef and oysters supply 3 micrograms, and other types of fish have less than 1 microgram. One cup of whole milk has about 2 micrograms, while a 1-ounce serving of cheese contains less than 1 microgram. The recommended daily intake for total vitamin K is 90 micrograms daily for women and 120 micrograms for men.

About the Author

Sandi Busch received a Bachelor of Arts in psychology, then pursued training in nursing and nutrition. She taught families to plan and prepare special diets, worked as a therapeutic support specialist, and now writes about her favorite topics – nutrition, food, families and parenting – for hospitals and trade magazines.